Southern Stay's Warrnambool office now occupies both sides of a northern Fairy Street lane to accommodate increasing staff numbers.

Chief executive Paul Lougheed said people using the service had increased from 200 in 2017 to about 600 this year.

He said the growth was due to a boom from the National Disability Insurance Scheme and a merger between Hamilton's Stay Residential Services and Warrnambool's Southern Way.

An 1884 building, formerly second-hand music store Thumbs Up Music Plus, was vacant for three years and now accommodates the organisation's administration and finance workers following a four-month renovation.

"Having a vacant building next door, it's an incredible alignment," Mr Lougheed said.

The service's main focus is on supported independent living for people with disability, and it operates 12 houses across Warrnambool and Hamilton.

The past two years have also seen increased employee numbers from 150 to 200.

While most work in the community is in private homes, the new offices can accommodate a further four workers.

"The level of growth since NDIS came in is just through the roof," Mr Lougheed said.

"All services have experienced similar growth, if you have a $22-billion-a-year initiative from the federal government, it's going to bring funding to our sector."

He said the sector was expecting that growth to level out in coming years, but demand from ageing parental carers seeking supported independent living for their children would continue.

From January next year the service will house nine young people in the south-west's first high physical support needs disability accommodation house built under the NDIS at Ryot Street, costing $2.6 million.

"That's going to be an area of growth," he said.

Have you signed up to The Standard's daily newsletter and breaking news emails? You can register below and make sure you are up to date with everything that's happening in the south-west.